If you do find a stiff spot, gently bend the chain laterally back and forth till it loosens up. It should only take like 2-3 wiggles.
Not to be rude but I'm in the gym and can't type much. Google track bike chain tension for videos.
If your chain is stiff and hard it's too tight. You should have about 1" of vertical play when the wheel is set.
Too tight is bad. It binds and wastes watts via friction.